1. Technical Field
The present invention relates to a nozzle discharge quantity correction method, a droplet discharging method, and an organic Electroluminescent (EL) device manufacturing method.
2. Related Art
According to the related art, a droplet discharging method (ink jet method) of forming a thin film by discharging liquid, containing a functional ingredient, from the nozzles of an ink jet head in the form of droplets has been known. A representative example of a thin film which is formed using the droplet discharging method is the emission layer of a color filter or an organic EL panel.
An ink jet head includes a plurality of cavities which store liquid, a plurality of nozzles which are in communication with the corresponding cavities and which are arranged in one direction, and a plurality of actuators (for example, piezoelectric elements, resistive heating elements, or the like) which pressurize the liquid in each of the cavities. The ink jet head receives a driving waveform signal which is common to the actuators which are selected based on the drawing data, and discharges droplets of liquid from the nozzles corresponding to the respective actuators. The ink jet method causes a thin film to be formed by discharging to a substrate liquid in the form of droplets from the nozzles of the ink jet head and then drying the droplets deposited on the substrate.
It is desirable that the ink jet method enable drawing which has excellent half-tones when a drawing target is displayed in high definition, and, for example, JP-A-2008-136927 discloses a droplet discharge head driving method enabling drawing which has excellent half-tones.
According to the droplet discharge head driving method, a plurality of different driving waveform signals corresponding to ranks which are set to an actuator are applied to nozzles selected based on the drawing data, so that the average weight of the droplets which are discharged can be determined as a predetermined weight which was predefined. Therefore, when the driving waveform signals generated for the respective ranks are combined, the total weight of the liquid (droplets) which is discharged onto a target can be calibrated for each nozzle, and the uniformity of film thickness obtained by drying the liquid can be improved. Furthermore, compared to the case where droplets are discharged using a single driving waveform signal, JP-A-2008-136927 discloses that the degree of accuracy, obtained when the average weight is adjusted, can be improved, and that the degree of freedom can be enlarged by just combining different driving waveform signals.
However, in the droplet discharge head driving method of ranking the average weight of the plurality of droplets, which is disclosed in JP-A-2008-136927, the gray scale to be ranked is limited, so that it is difficult to sufficiently correct the dispersion of the weight of the droplets.
When the dispersion of the weight of the droplets is not sufficiently corrected, heavy-weight droplets or light-weight droplets are continued along the scanning direction of a substrate. Therefore, even when the weight difference between the heavy weight droplets and the light weight droplets is minute, the difference is generated in the film thickness of a thin film, such as the emission layer of the color filter or the organic EL panel or the like, and the difference in the film thickness is reflected as high sensitivity when an electro-optical device performs display, so that there is a problem of lowering the image quality.